The reaction between NO 3 and R-pinene has been studied in large reaction chambers of 0.5-200 m 3 volume, using long path FT-IR, GC-ECD, and GC-FID for the analyses. The reaction yielded 62 ( 4% pinonaldehyde (3-acetyl-2,2dimethylcyclobutane acetaldehyde) and 3 ( 0.5% pinane epoxide. The total yield of alkylnitrates was estimated to be approximately 14%; two of the nitrates have been identified as 3-oxypinane-2-nitrate, and 2-hydroxy-3nitrate with yields of 3 ( 0.2% and 5 ( 0.4%, respectively. This work represents the first quantitative identification of pinonaldehyde and alkylnitrates from the reaction of NO 3 with R-pinene. A thermally stable peroxy acylnitrate was observed to be formed from secondary reactions of pinonaldehyde in the system. This compound has been assigned to 3-acetyl-2,2-dimethylcyclobutane acetylperoxynitrate. Possible implications for the atmospheric NO x chemistry are discussed. From the product data, a mechanism for the NO 3 + R-pinene reaction has been constructed.

Some aspects of the atmospheric chemistry of methyl thiolformate (CH 3 SCHO), a recently detected intermediate in the oxidation of dimethyl sulfide, have been investigated at 298 K and 1000 mbar total pressure in large reaction chambers using long path in situ FTIR absorption spectroscopy for the analysis. Rate coefficients of (1.11 ( 0.22) × 10 -11 and (5.80 ( 0.80) × 10 -11 cm 3 molecule -1 s -1 have been determined for its reaction with OH radicals and Cl atoms, respectively. The UV spectrum of CH 3 SCHO has been measured in the range 220-355 nm and a lower limit of 5.4 days determined for its atmospheric photolytic lifetime. Detailed product analyses have made for the OH and Cl initiated photooxidation of CH 3 SCHO. Strong SO absorption bands observed in both systems are tentatively assigned to CH 3 SOCHO in the OH system and to CH 3 SOCl in the Cl system. The first gas-phase spectra of CH 3 SCl and CH 3 SOCl are also presented. The results are discussed with respect to the atmospheric chemistry of CH 3 SCHO and possible consequences for the photooxidation mechanism of dimethyl sulfide.

FTIR product studies of the OH-radical-initiated oxidation of di-n-butoxymethane (DNBM) in the presence of NO x were performed in an indoor photoreactor and in the outdoor simulation chamber EUPHORE in Valencia, Spain. The reaction products observed in both reaction chambers were n-butoxymethyl formate (NBMF), propionaldeyhde, and di-n-butyl carbonate (DNBC). In the indoor reactor yields for NBMF and propionaldeyhde of 77 ± 15 and 78 ± 16 mol % were obtained in the system DNBM/MeONO/NO x /air/hν and 88 ± 18 and 69 ± 14 mol % in the system DNBM/H2O2/NO x /air/hν, respectively. In the outdoor chamber, yields of 80 ± 8 and 44 ± 11 mol % were obtained after sunlight irradiation of a DNBM/NO x /HONO/air mixture. For di-n-butyl carbonate (DNBC), an upper limit of ≤10 mol % was estimated for both reaction chambers. In the indoor photoreactor small amounts of n-butyl formate (NBF) and n-butoxymethyl butyrate (NBMB) were also detected with upper limits of 3 mol % for each compound. Bimolecular rate coefficients for the reactions of NBMF and DNBC with OH radicals were determined in the indoor photoreactor using the relative rate technique. Values of k OH+NBMF = (8.00 ± 0.91) × 10-12 cm3 s-1 and k OH+DNBC = (7.07 ± 1.64) × 10-12 cm3 s-1 were obtained. NBMF was synthesized and authentic samples were used for calibration. A photochemical mechanism was developed to describe the OH-initiated degradation of di-n-butoxymethane (DNBM) in the presence of NO x . The reaction scheme was tested by comparison of computer box model calculations and experimental data. Experimentally obtained and modeled concentration−time profiles for selected reactants are in excellent agreement.